Conception, pregnancy and delivery require an intricate and delicate interplay of physiology and anatomy. Implantation and placentation of the embryo are complex processes involving hormonal and anatomical changes in the mother and migration and cellular division of the embryo.
Spontaneous abortion occurs in 15% of diagnosed pregnancies in women between fifteen and forty-five years of age. Recurrent spontaneous abortions are defined as the loss of three or more consecutive pregnancies and occur in about 3-4% of these women. The risk of pregnancy loss increases from 15-20% in the first pregnancy to 40% after one spontaneous abortion.
Although the majority of pregnancies lost in the first trimester are due to fetal causes; spontaneous abortion, the loss of the product of conception prior to the 20th week of pregnancy, is a disorder of unknown etiology. It has been theorized that spontaneous abortions are a natural rejection of a fetus with abnormalities incompatible with life, however, this theory has yet to be substantiated.
Risk factors for abortion include age, weight and overall health of the woman. The prevalence of spontaneous abortion increases with increasing maternal age, although not with gravidity. The risk begins to increase rapidly at age 35 years. The risk of spontaneous abortion at age 40 is approximately twice that at age 20. As families are planned later and later in life, the frequency of spontaneous abortion will only increase without effective methods of prevention.
Accompanying the rising age of hopeful parents is the increasing use of assisted reproductive techniques such as in vitro fertilization, gamete intrafallopian tube transfer (GIFT), and the like. These techniques have their own attending risks, especially to the woman during ovarian hyperstimulation. Moreover, assisted reproduction and in vitro fertilization are costly, time consuming and have a high failure rate, resulting in pregnancy in only about 25% of cases. (see Merck Manual 17th edition, 1999, Merck Research Laboratories, Whitehouse Station, N.J., p. 1995).
Threatened abortion generally presents as cramping and bleeding for which treatment is bed rest. This conservative treatment provides palliative care for the mother but does little to alter the outcome. The use of hormones is generally contraindicated due to the risk of congenital anomalies, including malformation of the vessels of the heart of the embryo and possible genital abnormalities in female offspring.
Preeclampsia and other hypertensive disorders of pregnancy are a leading global cause of maternal and infant illness and death. Symptoms of preeclampsia include hypertension, edema and proteinuria with sudden weight gain, headaches and changes in vision. Preeclampsia can prevent the placenta from getting enough blood which can cause low birth weight and other problems for the baby. Although most women with preeclampsia still deliver healthy babies, some develop eclampsia, a serious condition that threatens the life of the mother and the fetus.
The risk of preeclampsia is higher in women carrying multiple babies, in teenage mothers and in women older than age 40. Typically, preeclampsia occurs in the late 2nd or 3rd trimesters (middle to late pregnancy) though occasionally it occurs earlier. Preeclampsia affects about 5% of all pregnancies.
Mild preeclampsia is conservatively treated with strict bed rest and vigilant monitoring of blood pressure. Progression of the disorder is treated with fluids, antihypertensives and magnesium sulfate but delivery of the fetus provides the only remedy.
In addition to the physical toll of these disorders, the loss of a desired pregnancy takes a tremendous emotional toll on hopeful and expectant parents. Loss of a pregnancy can lead to feelings of inadequacy, hopelessness and guilt which can have a devastating effect on individuals and on a marriage.
New methods and compositions are always needed to reduce risks associated with pregnancy to the health of the mother and fetus. Effective prevention of spontaneous abortion can allow women, especially women at risk, to have successful pregnancies, and effective treatment or prevention of preeclampsia can reduce or eliminate one of the common health risks of pregnancy. Prevention of implantation failure during assisted reproduction, can allow successful pregnancies, reduce the risks to the woman and save time and money. Prevention of pre term labor will enhance the likelihood of normal births.